New research supports theories that a collision with a wayward dwarf planet early in the history of the solar system best explains why the Moon’s farside features heavily cratered terrain compared to the nearside with its lower-lying basins.The stark difference between the two hemispheres was first noticed when spacecraft began beaming back images of the farside for the first time. NASA’s Gravity Recovery and Interior Laboratory – GRAIL – mission in 2012 revealed the crust on the farside is thicker than its nearside counterpart and includes an extra layer of material.Planetary scientists have debated several theories for the asymmetry over the years, including the merger of two moons very early in the solar system’s evolution or an impact with a dwarf planet later, after the Moon’s crust solidified.Carrying out a new study based on GRAIL gravity measurements, Meng Hua Zhu of the Space Science Institute at Macau University of Science and Technology and a team of researchers ran 360 computer simulations to test a variety of lunar impact scenarios in an attempt to reproduce the crust seen on the Moon today.“The detailed gravity data obtained by GRAIL has given new insight into the structure of the ...